The present invention relates generally to force sensors, and more specifically relates to improved force sensors sized and configured to be suitable for inclusion in a hand-held device, and to methods for constructing such input devices; and further to methods for sensing deflection in an input device as an indicator of direction of movement of the input device.
Input devices for computers and other processing systems, such as those typically referred to individually as a computer “mouse,” are well-known for use to provide data used to incrementally move an indicator such as a cursor on a display, to control the processing system. Many such “mice” operate through direct communication with an external surface. Well-known examples of such mice include various devices that operate through physical contact of a caged ball rolling on a support surface to provide an indication of movement through detection of the movement by orthogonally-arranged sensors detecting relative X-Y directional components of the ball movement, as it rolls in any direction relative to the surface. Similarly, mice are well-known which utilize an optical sensor to detect movement of the device relative to a support surface.
Input devices such as a computer mouse have recently been proposed by persons employed by the assignee of the present application, that function in the absence of the described physical or optical interaction with a support surface. These recently-proposed input devices operate using other types of sensors, as will be described in more detail later herein, without the need for such mechanical contact or optical elements. One example of such an input device is described in U.S. application Ser. No. 12/242,343, filed Sep. 30, 2008, and entitled “Method And Apparatus For Operating An Input Device,” the specification of which is hereby incorporated herein by reference for all purposes. These recently-proposed input devices maybe in the form of conventional devices such as those normally thought of as “ mice.” However, these input devices may also be of such other configurations as may be desired in any particular context to provide directional and/or positional input.
One example of such an input device utilizes a force sensor assembly to detect lateral force applied to the input device, such as by a user. This force detection is preferably made relative to at least two intersecting axes to provide resolution of the direction of movement in a single plane, i.e., relative to a supporting surface. In these recently-proposed input devices, a second sensor assembly is used to provide a measure of the speed of the movement. In some examples, a vibration sensor is used to provide this speed measure. Thus the two sensor assemblies together provide measures of the direction and speed of movement of the input device that can be combined to provide positioning data based on the movement of the mouse.
In these recently-proposed devices, although virtually any type of force sensor able to detect loading applied relative to at least two different axes could be utilized, optimal performance is believed to be best obtained by a force sensor constructed to withstand the rigors of use over an extended time period, and by potentially by multiple persons with a wide range of operating tendencies. While at the same time, the force sensor will preferably fit within a conventionally-sized input device form factor, and is preferably a device that may be relatively straightforward to manufacture without undue expense.